With popularity of terminals, a protective case of a terminal is used to not only protect the terminal, but also wake up the terminal when the protective case is turned over, or keep the terminal in a standby state when the protective case is closed.
Specifically, a mobile phone is used as an example. A patch of magnet is built into a side (flip side) of a protective case of the mobile phone, and the side is in contact with a mobile phone screen. A Hall device of the mobile phone senses a magnetic field of the magnet. As shown in FIG. 1, if the protective case of the mobile phone is partially opened, and the magnet is not within a sense range of the Hall device, that is, the Hall device cannot sense the magnetic field of the magnet, the mobile phone is woken up, and the screen is lit up.
However, when the mobile phone is in a rather jolting environment, even though the protective case is not fully opened, a relative position between the magnet of the protective case and the Hall device may change with a jolt. Therefore, the Hall device may be unable to sense the magnetic field of the magnet, and further, the mobile phone is woken up, and the mobile phone screen is lit up, causing a power waste of the mobile phone.